Search for Life Beyond Earth: Europa, Enceladus & the Future of Space Exploration

Susan Wise: Hi, and welcome to Stars Launch Pod: Space Technology and Research Sciences, brought to you by StarSciences.org, where we connect, collaborate, and accelerate. I’m your host, Susan Wise.

Please welcome Thomas O’Sullivan, planetary scientist and computational chemist, working on the search for life beyond Earth and specializing in the icy moons of Jupiter and Saturn.

This sounds really exciting. Thomas, welcome to our podcast.

Thomas O’Sullivan: Thank you for having me. Great to be here.

Susan Wise: Yes, I want to know more about you and what you’re doing to help further the space industry. This just sounds like a true passion for you.

Thomas O’Sullivan: Totally, yeah. So, I’m a scientist here in Berlin at the Free University, and we’re all about searching for life in the solar system—extraterrestrial life. We specialize, as you said, in the moons of Jupiter and Saturn.

What you’d expect to be quite cold places are actually able to host subsurface oceans of liquid water. These are sustained by heat from the gravitational pull of Jupiter and Saturn, as well as some of the other moons. This creates a warm, potentially habitable environment beneath an icy crust.

The moons in particular that we look at—one is called Europa at Jupiter, and we’ve got two missions on the way there at the moment, one from NASA and one from the European Space Agency. The other moon that we’re really interested in is Enceladus at Saturn, a really small moon about the size of the UK or Arizona.

What’s fascinating about it is that it has this plume at the south pole. This plume is like a cold volcano, ejecting material from the subsurface ocean. It gives us free samples.

We had a mission there about 20 years ago called Cassini, which finished about 10 years ago. Cassini flew through this plume and sampled ice grains and gas containing dissolved ocean material—quite complex chemistry. So really, these are fascinating environments.

Susan Wise: So when you’re searching for life, are you thinking on the microscopic level or something bigger?

Thomas O’Sullivan: Generally, a microscopic level. If you find something bigger, it’s a nice surprise. But the basic assumption is that we’re looking for simple, single-celled life.

Susan Wise: You’ve already gotten information back from the first moon you were talking about, right?

Thomas O’Sullivan: Yes, yeah. We’ve had missions at both before. But because Enceladus has this plume, you’re able to get these free samples of the ocean without having to drill through 20, 30, or 40 kilometers of ice that would otherwise block access.

When we flew through the plume—bearing in mind that the spacecraft wasn’t really designed to do this; it was a surprise discovery—Cassini had instruments called mass spectrometers. These give you information about the chemistry of a particle or gas you sample.

When we turned them on, we saw a range of organic and inorganic compounds, including quite complex organic molecules that look somewhat similar to what we might expect to find on Earth. It’s not enough to confirm life, but it’s certainly a good indication that we may be looking at habitable environments.

Susan Wise: Ah, that’s exciting. And that’s part of all the excitement right now because we went back to the Moon—or around the Moon—

Thomas O’Sullivan: Mm-hmm.

Susan Wise: And now eventually back to the Moon, I’m guessing, to get us ready to go further.

Thomas O’Sullivan: Yeah, absolutely. That’s what the Artemis program is all about. It’s an exciting time—not just for the icy moons of Jupiter and Saturn, but for Mars as well.

The last year or so has been really fascinating, with discoveries from the rovers on Mars—evidence of possible biosignatures contained in rocks. These include long-chain organic molecules that may be derived from something related to biology.

Susan Wise: Is there going to be a way to get samples and bring them back so you can actually get hands-on?

Thomas O’Sullivan: From Mars, yes—that’s always been the plan. It’s probably a bit delayed now, but Mars sample return has been on the agenda for years.

From the moons of Jupiter and Saturn, it’s a bit far for current technology. We’re generally looking at one-way missions that can do all their science in situ.

You may have orbiters or a lander. The European Space Agency is now planning to land on Enceladus, which would be the first landing there, to search for life directly.

With a lander, you can carry more complex instruments and be selective about the samples you collect. With orbiters, you’re essentially flying through and taking whatever hits your spacecraft. But it’s really exciting.

Susan Wise: I was just going to say, this is really exciting. It’s almost like a treasure hunt—you never know what you’re going to find. How long have you been on this journey?

Thomas O’Sullivan: I’m currently studying for my PhD—I’m two years into a three-year program. But really, for the last five years or so, I’ve been fascinated by these moons.

Susan Wise: Share one of your “aha” moments during this time.

Thomas O’Sullivan: Sure. We had a paper come out last year—my first major paper as a co-author. We discovered a range of new organic molecules in Cassini data from Enceladus’s plume.

These findings help piece together the bigger picture of what we’ve detected. We confirmed that the samples were derived directly from the subsurface and were collected just minutes after being ejected.

The types and distribution of compounds indicate a complex chemical network beneath the surface. Hopefully, this will spark further studies—lab simulations, computational models—and help build a better understanding of what’s happening on a moon billions of miles away.

It’s incredible to be part of that.

Susan Wise: What’s been one of your biggest challenges, and how did you overcome it?

Thomas O’Sullivan: In academia, the biggest challenge is always funding. There’s constant competition for grants and scholarships.

I’ve been working with my group in Berlin for about four years. The goal was always to pursue a PhD, but there wasn’t funding available. So we spent about a year writing a research proposal, collaborating with NASA partners, and fortunately, it was approved.

There was uncertainty for a while, but it worked out in the end.

Susan Wise: With space becoming more commercialized, is that a potential funding avenue?

Thomas O’Sullivan: Definitely—it’s an emerging area. But for missions focused purely on science and the search for life, there’s not always a clear financial return.

There’s huge societal value and long-term benefits, but monetarily it’s less obvious. So when competing for funding, you’re often up against projects with more immediate commercial impact.

Susan Wise: When experiments are conducted on these missions, is it AI-driven, or is someone controlling it?

Thomas O’Sullivan: Good question. There are generally three aspects: the mission is controlled by a space agency, instruments are often built by universities, and there’s a science team supporting it.

We’re starting to see more AI and machine learning involved. But traditionally, commands are uploaded manually, and the spacecraft operates semi-autonomously due to time delays—especially at Saturn.

Sometimes data has to be processed onboard because of limited bandwidth. Ideally, everything would be sent back for analysis, but that’s not always possible.

Susan Wise: Has this always been your dream?

Thomas O’Sullivan: Pretty much. I’ve been fascinated by space since I was a child. I studied astrophysics for my bachelor’s and realized this could be my career.

I later attended the International Space University in France, which was an amazing interdisciplinary experience—covering everything from space medicine to law to engineering and planetary science.

Susan Wise: How big is your team?

Thomas O’Sullivan: Our icy moons group has about 15–20 people, from students to senior professors. It’s an international, collaborative, and very supportive environment.

Susan Wise: Do you have any advice for listeners?

Thomas O’Sullivan: Space is more than just technology. There’s still so much science to discover. Deep space missions are incredibly exciting because we’re answering fundamental questions—like whether life exists beyond Earth.

Susan Wise: What’s your personal opinion—do you think life exists out there?

Thomas O’Sullivan: There’s no definitive answer, but I believe there is. Of course, you have to remain objective—but that belief is what drives me.

Susan Wise: Before we wrap up, do you have a passion project you’d like to share?

Thomas O’Sullivan: Yes—I work with an organization called Europlanet, a European planetary science nonprofit. I co-chair an early-career committee, and it’s been a great way to connect with scientists from around the world and build a collaborative community.

Susan Wise: That’s fantastic. Thomas, thank you so much for joining us.

Thomas O’Sullivan: Thank you—it’s been really nice talking to you.

Susan Wise: Thanks. And make sure you join us where we connect, collaborate, and accelerate. If you enjoyed this episode, please leave a review and subscribe. Until next time—keep looking up.